Pulverizer



P. R. CASSIDY June 15, 1937.

PULVER IZER Filed Nov. 9, 1933 3 Sheets-Sheet l INVENTOR perr ygcassiay June 15, 1937. P. R. CASSIDY 2,083,941

PULVERIZER Filed Nov. 9, 1955 3 Sheets-Sheet 2 43 :a e a INVENTOR b erry 1Q. Cassia y B ATTORN EY June 15, 1937. P. R. CASSIDY PULVERIZER Filed Nov. 9, 1933 3 Sheets-Sheet 5 INVENTOR Perry P. Cassidy A ORNEY Patented June 15, 1937 UNITED STATES PATENT QFFlCE The Babcock & Wilcox Company, Newark, N'. J1.

a corporation of New Jersey Application November 9, 1933, Serial No. 697 299.

13 Claims.

The present invention relates to apparatus for pulverizing materials such as coal, cement clinker, limestone, phosphate rock, etc., and more. particularly to pulverizers having upper, intermediate and lower relatively moving grinding rings between which rows of rolling grinding elements are positioned. In pulverizers of this type, the material to be pulverized is first passed through the upper row or rows of grinding elements. The partly ground material then passes by gravity to the lower row of elements where the final grinding action takes place. In such mills the intermediate ring is usually the driving ring and the upper and intermediate rings are arranged to float to permit the elements to pass over any substantially ungrindable obstructions in their path. The upper row or rows of elements are in operation subjected to a substantial grinding pressure which is transmitted through the floating intermediate ring to the lower row of elements and lower grinding ring. The lower row of elements and lower grinding ring are thus subjected to not only the grinding pressure exerted on the upper row'or rows of elements, butalso to the weight of the upper elements and upper and intermediate grinding rings. While ordinamy the grinding pressure per element exerted on the lower row of elements is desirably greater than the pressure exerted on the upper elements, I have found that with the proper grinding pressure in the upper elements the grinding pressure on the elements in the lower row may be higher than is necessary to secure the desired grinding eifect, and that the excess grinding pressure 5 causes an unnecessary increase in the power consumption of the mill and wear on the lower grinding parts. This undesirable condition is especially present in pulverizers of the type described having the grinding elements arranged 40 in a plurality of upper concentric rows and a single lower row.

The general object of my invention is the provision of a pulverizer of the general character described which includes adjustable provisions for substantially decreasing the grinding pressure on the lower row of grinding elements and correspondingly reducing the power consumption of the pulverizer and wear on the lower grinding parts. A more specific object is the provision of means independent of the lower row of elements and lower grinding ring for resiliently supporting the floating intermediate grinding ring and parts carried thereby. A further specific object: is a pulverizer having provisions tending to keep its intermediate ring in alignment with the drive shaft and to reduce the vibration and noise of the pulverizer.

The various features of novelty which characterize my invention are pointed outwith particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred embodiments of my invention.

Of the drawings:

l is a sectional elevation of a gravity fiow multi-stage pulverizer embodying my invention;

Fig. 2 is an enlarged view of a portion of Fig. 1, taken on the line 2-2- of Fig. 4;

Fig. 3 is a section taken on the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary plan view of the mechanism shown in Fig. 2;

Fig. 5 is a viewcorresponding to Fig. 4 illustrating a modification, and

Fig. 6 is a. view corresponding to Fig. 2 taken on the line 6-6 of Fig. 5.

In the drawings I have illustrated a pulverizer of the type shown in my prior joint application, Serial No. 612,758, filed May 21, 1932 in which the reference numeral l U designates a cylindrical pulverizer casing having one or more feed spouts l 1 opening into the upper part thereof, and a discharge spout l2 in its lower side wall. The casing l0 encloses concentric inner and outer upper rows of rolling grinding elements l3 and M respectively, preferably asshown, in the form of heavy metallic grinding balls. The rows of balls l3 and M are arranged in corresponding tracks formed inthe upper surface of a rotary floating intermediate grinding ring IS; the central part of which is closed by-a conical material receiving cover plate IS. The balls I3 and M respectively support floating upper non-rotary grinding rings I! and I8. The balls l3 forming the inner grinding stage are advantageously of larger diameter than the balls M; The upper grinding rings H and l 8- are subjected to independently adjustable grinding pressures by means of a series of helical pressure springs 20 arranged in a circular row in pockets formed in the top plate of the casing l0: and pressure adjusting screws IS.

The floatingintermediate ring I5 is supported on a lower circular-row of grinding-balls 2 l' which in turn move ina trackiormedin the upper surface of a lower non-rotary grinding ring 22, which is secured: in position. The drivemecha- 2 nism for the pulverizer comprises a vertical drive shaft 23 extending upwardly axially of the casing It and driven from a pinion shaft 24 through beveled gears 25 and 26, stub shaft 2?, and spur gears 28 and 29, and maintained in its vertical operating position by vertically spaced roller bearings 3|. At the upper end of the drive shaft is secured a substantially cylindrical drive yoke 32,

which carries at its lower end one or more sweep plates 33 by which the pulverized material leaving the inner side of the balls 2! is swept into the outlet spout l2. The intermediate grinding ring I5 is driven from the drive shaft 23 through a floating drive connection formed by a plate 35 on the drive yoke which is positioned between a pair of vertical guide plates 36 carried at the inner side of the intermediate ring 15.

With the construction described, the material entering through the feed spout I l drops onto the rotary cover plate inner balls IS. The material passes radially outwardly through the ball rows l3 and i4, and

by gravity through an adjustable ledge gap 31 to and then radially inwardly through the lower ball row 2 I.

With the described construction the rows of balls l3 and it are independently subjected to the pressure of the springs 28 and the weight of the corresponding upper rings l! and it to pro vide an effective grinding action on the material passing therethrough. The grinding pressure per ball in the two upper rows is preferably sub stantially the same, for example, 1750 lbs. per ball. The pressure on the lower balls 2! and on the lower ring 22 will be considerably higher as the lower balls are subjected to not only the combined grinding pressures on the upper rows of balls but also to the dead weight of the upper and intermediate grinding rings and the upper rows of balls. The pressure in the lower balls may be as high as 4072 lbs. per ball, whereas a grinding pressure of about 2300 lbs. per ball on the lower balls is sufficient for carrying out the desired final pulverization in the lower row. The excess grinding pressure substantially increases the amount of energy required to rotate the intermediate grinding ring and balls associated therewith relative to the non-rotary rings. It also causes the balls 2| and contacting surfaces of the grinding rings 15 and 22 to rapidly wear and require relatively rapid replacement.

In accordance with my present invention, the power consumption of the pulverizer and wear on the lower grinding parts are substantially reduced and other desirable results attained by substantially reducing the pressure on the lower row of grinding balls 2! and lower grinding ring 22 by incorporating adjustable supporting provisions for the intermediate ring which are inde- 60 pendent of the lower ball row and grinding ring.

As shown in Figs. 1 to 4, the supporting provisions may advantageously consist of a series of leaf springs 40 mounted on the top, and extending radially, of the drive yoke 32. The outer ends of the leaf springs support and are connected to the under side of the intermediate grinding rings, as indicated at 4|, while the inner end of each spring is adjustably compressed by a bar 42 extending over the inner ends of a group of the springs 46 and vertically slideable in spaced guide posts 43 arranged intermediate the spring groups. Bolts 46 extend through each bar 42 and nuts 41 on each bolt prevent upward movement of the corresponding bar and provide a means for adjustment of the position of the spring so as to 56., and is delivered to the control the load carried by the springs. The plates forming each spring are bound together at their middle points by a detachable clamp 44 positioned in a recessed boss 45 formed on the upper surface of the drive yoke and serving as the fulcrum of the spring. The springs 40 provicle an adjustable reaction between the drive yoke and intermediate grinding ring, which substantially reduces the grinding pressure on the balls of the lower row. These springs also tend to keep the floating intermediate grinding ring concentric with the drive shaft and by their shock absorbing action reduce the vibration and noise in the mill. The portion of the load carried by the springs is transmitted through the drive shaft 23 to a thrust bearing 30 at the lower end of the drive shaft.

In the modification illustrated in Figs. 5 and 6, the leaf springs shown in Figs. 1 to 4 are replaced by a circular row of helical springs 50 positioned in sockets 5| formed in the drive yoke 32 adjacent its periphery. The position of the springs is maintained by circular centering plates 52 detachably secured to the yoke and intermediate ring at points within the opposite ends of the springs 50. The lower end of each spring 50 abuts the upper side of one or more removable circular shims 53, the number of which in use determines the supporting capacity of the corresponding helical spring.

While in accordance with the provisions of the statutes I have illustrated and described herein the best forms of my invention now known to me,

those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use.

of other features.

I claim:

1. A pulverizer comprising a casing enclosing an upper circular row of rolling grinding elements, a rotary floating intermediate grinding ring arranged to support said upper row of elements, a non-rotary upper grinding ring supported on said upper row of elements, means for exerting a grinding pressure on said upper row of elements, a lower non-rotary grinding ring, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings, said lower row of elements and grinding ring being arranged toreceive the weight of and pressure exerted on said floating intermediate grinding ring, a vertically fixed drive shaft, means forming a floating drive connection between said drive shaft and intermediate grinding ring, and means independent of said lower row of elements and grinding ring for resiliently supporting said intermediate grinding ring in a floating position.

2. A pulverizer comprising a casing enclosing an upper circular row of rolling grinding elements, a rotary floating intermediate grinding ring arranged to support said upper row of elements, a non-rotary upper grinding ring supported on said upper row of elements, means for exerting a grinding pressure on said upper row of elements, a lower non-rotary grinding ring, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings, said lower row of elements and grinding ring being arranged to receive the weight of and pressure exerted on said floating intermediate grinding ring, a vertically fixed drive shaft, a drive yoke mounted'on said shaft, means forming a floating drive connection between said drive yoke and intermediate grinding ring, and means for resiliently supporting said intermediate grinding ring in a floating position from said drive yoke.

3. A pulverizer comprising a casing enclosing inner and outer upper concentric rows of rolling grinding elements, a rotary floating intermediate grinding ring arranged to support said inner and outer rows of elements, inner and outer con centric non-rotary upper grinding rings respectively supported on said inner and outer rows of elements, means for exerting a grinding pressure on said inner and outer rows of elements, a lower non-rotary grinding ring, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings, said lower row of elements and grinding ring being arranged to receive the weight of and pressure exerted on said floating intermediate grinding ring, a drive shaft, means forming a floating drive connection between said drive shaft and intermediate grinding ring, and means independent of said lower row of elements and grinding ring for resiliently supporting said intermediate grinding ring.

4. A pulverizer comprising a casing enclosing inner and outer upper concentric rows of rolling grinding elements, a rotary floating intermediate grinding ring arranged to support said inner and outer rows of elements, inner and outer concentric non-rotary upper grinding rings respectively supported on said inner and outer rows of elements, means for exerting a grinding pressure on said inner and outer rows of elements, a lower non-rotary grinding ring, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings, said lower row of elements and grinding ring being arranged to receive the weight of and pressure exerted on said floating intermediate grinding ring, a drive shaft, a drive yoke mounted on said shaft, means forming a floating drive connection between said drive yoke and intermediate grinding ring, and

' means for resiliently supporting said intermediate grinding ring from said drive yoke.

5. A pulverizer comprising a casing enclosing inner and outer upper concentric rows of rolling grin-ding elements, a rotary floating intermediate grinding ring arranged to support said inner and outer rows of elements, inner and outer concentric upper grinding rings respectively supported on said inner and outer rows of elements, means for exerting independently adjustable grinding pressures on said inner and outer rows of elements, a lower non-rotary grinding ring arranged below said outer row of elements, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings, said lower row of elements and grinding ring being arranged to receive the weight of and pressure exerted on said floating intermediate grinding ring, a drive shaft, a drive yoke mounted on said shaft, means forming a floating drive connection between said drive yoke and intermediate grinding ring, and means for resiliently supporting said intermediate grin-ding ring from said drive yoke.

6. A pulverizer comprising a casing enclosing inner and outer upper concentric rows of roll ing grinding elements, a rotary floating intermediate grinding ring arranged to support said inner and outer rows of elements, inner and outer concentric non-rotary upper grinding rings respectively supported on said inner and outer rows of elements, means for exerting a grinding pressure on said inner and outer rows of elements, a lower non-rotary grinding ring, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings said lower row of elements and grinding ring being arranged to receive the weight of and pressure exerted on said floating intermediate grinding ring, a drive shaft, a drive yoke mounted on said shaft, means forming a floating drive connection between said drive yoke and intermediate ring, and means independent of said lower row of elements and grinding ring for resiliently supporting said intermediate grinding ring comprising a series of circumferentially spaced leaf springs fulcrumed on said drive yoke and having their opposite ends connected to said drive yoke and intermediate grin-ding ring.

7. A pulverizer comprising a casing enclosing inner and outer upper concentric rows of rolling grinding elements, a rotary floating intermediate grinding ring arranged to support said inner and outer rows of elements, inner and outer concentric non-rotary upper grinding rings respectively supported on said inner and outer rows of elements, means for exerting a grin-ding pressure on said inner and outer rows of elements, a lower non-rotary grinding ring, a lower circular row of rolling grinding ele.- ments positioned between said intermediate and lower grinding rings, said lower row of elements and grinding ring being arranged to receive the weight of and pressure exertedon said floating intermediate grinding ring, a drive shaft, a drive yoke mounted on said shaft, means forming a floating drive connection between said drive yoke and intermediate ring, and means independent of said lower row of elements and grinding ring for resiliently supporting said intermediate grinding ring comprising a series of circumferentially spaced helical springs positioned between said intermediate grinding ring and said drive yoke.

8. A pulverizer comprising a circular row of rolling grinding elements, a lower grinding ring arranged to support said row of elements, a rotary floating upper grinding ring supported on said row of elements, a vertically fixed drive shaft, a drive yoke mounted on said shaft, means forming a floating drive connection between said drive yoke and floating grinding ring, and resilient ring supporting means extending between said floating grinding ring and said drive yoke.

9. A pulverizer comprising a casing enclosing a circular row of rolling grinding elements, a lower non-rotary grinding ring arranged to support said row of elements, a rotary floating upper grinding ring supported on said row of elements, means for exerting a grinding pressure on said floating grinding ring, said row of elements and lower grinding ring being arranged to receive the weight of and pressure exerted on said floating grinding ring, a vertically fixed drive shaft, a drive yoke mounted on said shaft, means forming a floating drive connection between said drive yoke and floating grinding ring, and resilient ring supporting means extending between said floating grinding ring and said drive yoke.

10. A pulverizer comprising a lower grinding ring, a row of rolling grinding elements supported on said lower ring, a rotary intermediate grinding ring supported on said lower row of elements, an upper row of rolling grinding elements supported on said intermediate grinding ring, an upper grinding ring supported on said upper row of elements, a vertically fixed drive shaft, means forming a floating drive connection between said drive shaft and intermediate grinding ring, and means independent of said lower row of elements and lower grinding ring for resiliently supporting said intermediate grinding ring in a floating position.

11. A pulverizer comprising a lower grinding ring, a row of rolling grinding elements supported on said lower ring, a rotary grinding ring supported on said row of elements, a vertically fixed drive shaft, means forming a floating drive connection between said drive shaft and rotary grinding ring, and means independent of said lower row of elements and lower grinding ring contacting with and resiliently supporting said rotary grinding ring in a floating position.

12. A pulverizer comprising a casing enclosing an upper circular row of rolling grinding elements, a rotary floating intermediate grinding ring arranged to support said upper row of elements, a non-rotary upper grinding ring supported on said upper row of elements, means for normally exerting a grinding pressure on said upper row of elements, a lower non-rotary grinding ring, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings, said lower row of elements and grinding ring being arranged to receive the weight of and pressure exerted on said floating intermediate grinding ring, means arranged to deliver material to be pulverized successively to said upper and lower rows of grinding elements, and means independent of said lower row of elements and grinding ring for resiliently supporting said intermediate grinding ring in a floating position, said last mentioned means being rotatable with said intermediate grinding ring and arranged to reduce the grinding pressure on said lower row of grinding elements.

13. A pulverizer comprising a casing enclosing an upper circular row of rolling grinding elements, a rotary floating intermediate grinding ring arranged to support said upper row of elements, a non-rotary upper grinding ring supported on said upper row of elements, means for normally exerting a grinding pressure on said upper row of elements, a lower non-rotary grinding ring, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings, said lower row of elements and grinding ring being arranged to receive the weight of and pressure exerted on said floating intermediate grinding ring, means arranged to deliver material to be pulverized successively to said upper and lower rows of grinding elements, means independent of said lower row of elements and grinding ring for resiliently supporting said intermediate grinding ring in a floating position, said last mentioned means being rotatable with said intermediate grinding ring and arranged to reduce the grinding pressure on said lower row of grinding elements, and means for adjusting the supporting effect on said last mentioned means.

PERRY R. CASSIDY. 

